Coccidiosis is a common and widespread poultry disease caused by species of protozoan parasites of the genus Eimeria. The most important of these species are E. maxima, E. acervulina, E. tenella, E. necatrix and E. brunetti. In turkeys, E. meleagridis and E. adenoides are also causative organisms of coccidiosis. When left untreated, the disease leads to poor weight gain, reduced feed efficiency and high mortality. For these reasons, the control of coccidiosis is highly important to the poultry industry. Although E. tenella and E. necatrix cause the most lethal forms of the disease, it is known that infections due to other species, and particularly to the so-called intestinal species such as E. acervulina, E. brunetti and E. maxima, also present a serious economic problem.